The present invention relates to electronic differential line drivers and particularly to low power ECL, or emitter coupled logic, line drivers used to drive a predetermined amount of electrical power through a line or load. The present invention further relates to differential ECL line drivers operating with relatively high efficiency particularly useful in high density, monolithic switching circuitry.
Conventional differential ECL line drivers employ emitter resistors in each side of the amplifier. Such amplifiers are not efficient because power is consumed in both emitter resistors at all times even though power is only required on one side at a time. In circuitry in which only a small number of differential line drivers are used, the power consumed may not be of great importance, but in high density monolithic applications or large systems in which many such line drivers are used, any demonstrable improvement in power efficiency is important.
Therefore, what is desired is a differential ECL line driver configuration in which the power consumption is minimized.